The present invention relates to an endoscope system, and more particularly, to an endoscope system with an electric bending mechanism for electrically bending an insertion section.
In use, an insertion section of an endoscope is inserted into a coelom of a living body (such as a patient) and is bent in such a way as an operator (such as a doctor) desires for diagnosis. In recent years, there has been proposed an endoscope system with a motor-driven bending mechanism for electrically bending an insertion section including a flexible tube by means of a motor, for improving a bending operation of the insertion section of an endoscope.
In a practical use of the endoscope, which is designed for specific mechanical purposes, the insertion section of the endoscope is directly inserted into a coeliac cavity of a living body, such as the stomach, intestines and the like. In bending the insertion section of the endoscope in the coeliac cavity, great care must be taken so as not to impair the coelom. To this end, a subtle and precise control of the motor drive strictly according to the wishes of the operator is required for the bending operation of the endoscope insertion section. Further required is to accurately know an actual direction and an actual amount of the bending of the insertion section inserted and now present in the coelom. Otherwise, the distal end of the insertion section is excessively and uncontrollably bent to possible impair or, more adversely, break the inner wall of the coelom.
So far as we know, there have been no endoscope systems with a motor-driven bending mechanism which satisfactorily meet the technical requirements mentioned above. For example, an endoscope system disclosed in Japanese Utility Model Unexamined Publication No. 53-45790 is comprised of a motor, a manually operating member for controlling the drive of the motor, and a mechanical displacing member provided close to the operating member and mechanically displacing according to a bending angle of the insertion section of the endoscope. In order to know an actual amount of the bending of the insertion section in the coelom, an operator must contact the displaced member by hand. The prior endoscope mechanism employs a mechanical means for detecting the actual bending angle of the insertion section. Because of the nature of the mechanical means, it is very difficult to reliably and accurately control the bending operation of the insertion section in quick response to the operator's wishes. The mechanical means employed in the prior endoscope system needs a number of mechanical parts and a complex assembly of these parts. This results in a complicated structure of the endoscope system. It is therefore very difficult to obtain satisfactory reliability in the bending control of the insertion section of such an endoscope apparatus.